Question 1: Define bacteria and describe their basic cell structure.

Answer: Bacteria are microscopic, single-celled organisms that have a cell wall, cell membrane, cytoplasm, and genetic material, but lack a nucleus.

Question 2: Explain the process by which bacteria reproduce and how this affects their populations.

Answer: Bacteria reproduce mainly by binary fission, where a single cell divides into two identical daughter cells, leading to rapid population growth under suitable conditions.

Question 3: List two ways bacteria can be beneficial to humans.

Answer: Bacteria help in digesting food in the gut and are used in the production of antibiotics and fermented foods.

Question 1: A bacterial culture starts with 1,000 bacteria. If the bacteria double every 20 minutes, how many bacteria will there be after 2 hours?

Answer: 64000

Question 2: Calculate the growth rate (per hour) of bacteria that doubles every 30 minutes.

Answer: Approximately 2.52 (or 252%)

Question 1: Describe a safe method to investigate the effect of antibiotics on bacteria in a laboratory setting.

Answer: Use sterile techniques to prevent contamination, work in a sterile environment such as a laminar flow cabinet, wear protective clothing, and dispose of bacterial cultures safely after the experiment.

Question 2: Identify three variables that should be controlled in an experiment testing bacterial growth rates.

Answer: Temperature, nutrient availability, and pH levels.

Question 1: A bacterial population is observed to increase from 500 to 4000 over a 4-hour period. Calculate the average growth factor per hour.

Answer: Approximately 2.52 times per hour

Question 2: Based on the data, discuss what factors could have contributed to the rapid growth of bacteria.

Answer: Factors may include optimal temperature, high nutrient availability, suitable pH, and absence of antibiotics or other inhibitory substances.

Question 1: Explain how bacteria can cause disease in humans, including the mechanisms they use to infect and damage host tissues. (6 marks)

Answer: Bacteria cause disease by invading host tissues, producing toxins, and damaging cells. They can enter the body through cuts, the respiratory or digestive system. Some bacteria produce harmful substances that interfere with normal cell functions, leading to symptoms of illness.

Question 2: Describe two methods used to prevent bacterial infections.

Answer: Practising good hygiene and vaccination.

Question 1: Explain how bacteria are utilised in the food industry, providing two examples.

Answer: Bacteria are used in the production of yoghurt and cheese through fermentation processes.

Question 2: Discuss the impact of antibiotic resistance in bacteria and its implications for healthcare.

Answer: Antibiotic resistance leads to bacteria that no longer respond to standard treatments, making infections harder to treat, increasing healthcare costs, and raising the risk of severe illness or death. It necessitates the development of new antibiotics and stricter antibiotic usage policies.